This invention relates to dispensing fluids or other flowable materials, such as liquids, viscous creams, oils, pastes, granules, powders. It is particularly, but not exclusively, concerned with pressurization and pressurized delivery of liquids for consumption, such as beverages. Prime examples include water and beer, such as real ale. Preserving the longevity, integrity and taste for consumption are particular concerns. Thus air in contact with a beverage can trigger or promote deterioration, such as when in the case of real ale secondary fermentation is ongoing. Some aspects involve liquid and gas mixtures, or gas dissolved into solution, such as gasified or aerated admixtures. Other aspects might also be applied to other products and formulations, including creams, detergents, cleansers or soaps.
Confinement and containment must address both passive load such as static weight and active or dynamic loads from movement and acceleration in transit.
Strict regulatory health and safety hygiene considerations apply for products for human consumption. The Applicant envisages these be met by special isolation and containment provision according to the invention preserved until discharge or dispensing. Cross-contamination concerns, particularly with human contact and associated bacteriological transfer can also apply to a wider range of products.
One consideration, for a palatable product with satisfactory olfactory (taste and smell) sensation, is the amount of dissolved air and a facility to aerate or de-aerate prior to or upon dispensing. An example is beer, which is predominantly water and has been made from local spring water, such as from a ‘pure’ or unadulterated mountain spring water. Beer is available in bulk in barrels or casks for onward dispensing at a point of sale, and for personal consumption in bottles and in cans. In either case sealing of the container after filling is usual, not least when the content is pressurized, such as carbonated or aerated. A traditional manner of storage and dispensing is as a so-called ‘draught’; meaning drawn from storage in bulk in any kind of canister, cask, keg etc. Draught beer is usually unpasteurized and kept cool, otherwise it may turn sour and cloudy in a few days. It can be drawn by a hand pump from a barrel. Some canned and bottled bears are marketed as draft on the basis of taste similarities.
It is also common to dispense so-called traditional or ‘real ales’ through a pump from a barrel container or cask. That is without above atmospheric gas pressure and risk of aeration. It can be regarded as akin to traditional draught beer in the sense that is drawn or dragged or pumped up from a reservoir. However, the contents rapidly age with taste deterioration once a barrel has been opened or uncorked to allow ingress of air. A cask commonly features a tap hole near a top edge and a side hole for conditioning. Cask beer is drawn at cellar temperature of around 12° C., so is vulnerable to deterioration, once a cask plug seal has been removed and the cask ‘tapped’ to connect to a hand pump.
Beer is vulnerable to unsettling disturbance by shaking, dropping, churning or sudden high pressurization, with risk of natural sedimentation being raised and recirculated, which can in turn impair visual appearance and taste. In cask or so-called ‘real’ ale the yeast and fermentation can still be active. Foaming upon dispensing allows carbon dioxide to escape. A hand pump is commonly used for real ales, but needs to be primed and if mishandled can induce unintended frothing or aeration upon delivery.
Lately, so-called ‘keg’ beer has been specially developed as a brewing formulation to allow dispensing through a tap valve from pressurized, suitably robust and reinforced, generally metal, container vessels to inhibit hazardous split or rupture and wasteful contents discharge spillage. A keg of draft beer could last 20-30 days before perceptible taste and aroma deterioration occur to an unpalatable degree. Keg beer is drawn from a pressurized keg, commonly charged with an external gas supply, such as nitrogen or carbon dioxide or a mixture of the two from a gas bottle or cylinder. Such artificial carbonation is after fermentation has concluded. Keg beer is pasteurized and filtered to prolong its storage life, although with an impact upon its taste.
A keg commonly has a single opening in the top center for a flow pipe and is artificially pressurized after fermentation with a mixture of carbon dioxide and nitrogen gas. The headspace above the beer to be dispensed is pressurized with gas, so the delivery pipe charge requiring only opening of a low effort valve at the point of dispensing. Some gasification and frothing of the product such as to form a head upon delivery, may be admitted as expected by the consumer. Above atmospheric pressure allows the product to be lifted from a low level, such as a basement cellar, to a bar counter serving level possibly a story or more above. This requires careful regular cleaning of long feed lines from a remote vessel, such as one located in a cool underlying cellar, to a dispensing head at a point of service such as a bar counter.